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Performance deficits in a voluntary saccade task in Chinese "express saccade makers".

Knox PC, Amatya N, Jiang X, Gong Q, Gong Q - PLoS ONE (2012)

Bottom Line: Differences in behaviour and cognition have been observed in different human populations.However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks).These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population.

View Article: PubMed Central - PubMed

Affiliation: Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom. pcknox@liv.ac.uk

ABSTRACT
Differences in behaviour and cognition have been observed in different human populations. It has been reported that in various types of complex visual task, eye movement patterns differ systematically between Chinese and non-Chinese participants, an observation that has been related to differences in culture between groups. However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks). These participants are defined as "express saccade makers" (ESMs). We then show using the antisaccade paradigm, which requires the inhibition of reflexive responses and the programming and execution of voluntary saccades, that the performance of ESMs is compromised; they have higher antisaccade directional error rates, and the latency distributions of their error saccades again exhibit a higher proportion of low latency express saccade errors consistent with a reduced ability to inhibit reflexive responses. These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population. They suggest a potential unexpected confound relevant to those studies of Chinese versus other groups which have investigated group differences using oculomotor measures, and explained them in terms of culture. The confirmation of higher numbers of ESMs among Chinese participants provides new opportunities for examining oculomotor control.

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Relationship between prosaccade (PS) and antisaccade (AS) performance.A. Median prosaccade latency and AS directional error rate. B. Percentage of express saccades in the PS task and AS directional error rate. C. Median PS latency and median AS prosaccade error latency. D. Percentage of express saccades in the PS task and median AS error prosaccade latency (AS). E. Percentage of express saccades in the PS task and percentage of ES in AS prosaccade errors. F. The difference between correct AS latency and PS latency calculated for each subject, and AS directional error rate. On each plot the solid black line is the least-squares linear regression line calculated for the whole dataset. Data from ESMs: grey symbols; data from normal subjects: black symbols.
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pone-0047688-g006: Relationship between prosaccade (PS) and antisaccade (AS) performance.A. Median prosaccade latency and AS directional error rate. B. Percentage of express saccades in the PS task and AS directional error rate. C. Median PS latency and median AS prosaccade error latency. D. Percentage of express saccades in the PS task and median AS error prosaccade latency (AS). E. Percentage of express saccades in the PS task and percentage of ES in AS prosaccade errors. F. The difference between correct AS latency and PS latency calculated for each subject, and AS directional error rate. On each plot the solid black line is the least-squares linear regression line calculated for the whole dataset. Data from ESMs: grey symbols; data from normal subjects: black symbols.

Mentions: The two groups, defined on the basis of their performance on the prosaccade task, exhibited different patterns of performance in the antisaccade task. What then of the relationship between performance in the two different tasks? Performance in the prosaccade task was summarised using median saccade latency for each participant and the percentage of express saccades. We investigated the relationship between these parameters and antisaccade directional error rate (expressed as a percentage) and median ErrPS latency (Figure 6). Antisaccade directional error rate was correlated both with the median latency in the prosaccade task (Figure 6A; r = −0.33, p = 0.003) and with the percentage of express saccades (6B; r = 0.36, p = 0.002). Correlation coefficients were slightly higher between the median prosaccade latency and antisaccade error prosaccade latencies (6C; r = −0.55, p<0.0001) and percentage of express saccades in prosaccade tasks and antisaccade prosaccade error latency (6D; r = 0.43, p<0.0001). The highest correlation coefficient was observed for the relationship between the percentage of express saccades in prosaccade tasks, and the percentage of ErrPS that were express saccades (Figure 6E; r = 0.63, p<0.0001). We also examined whether a general difference in the speed of prosaccade and antisaccade systems might have a strong influence on directional error rate. For each participant we calculated the difference between the median correct antisaccade latency and the median prosaccade latency, and plotted this against the antisaccade directional error rate (Figure 6f). While there was a positive correlation, it was modest (r = 0.32, p = 0.004).


Performance deficits in a voluntary saccade task in Chinese "express saccade makers".

Knox PC, Amatya N, Jiang X, Gong Q, Gong Q - PLoS ONE (2012)

Relationship between prosaccade (PS) and antisaccade (AS) performance.A. Median prosaccade latency and AS directional error rate. B. Percentage of express saccades in the PS task and AS directional error rate. C. Median PS latency and median AS prosaccade error latency. D. Percentage of express saccades in the PS task and median AS error prosaccade latency (AS). E. Percentage of express saccades in the PS task and percentage of ES in AS prosaccade errors. F. The difference between correct AS latency and PS latency calculated for each subject, and AS directional error rate. On each plot the solid black line is the least-squares linear regression line calculated for the whole dataset. Data from ESMs: grey symbols; data from normal subjects: black symbols.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3472994&req=5

pone-0047688-g006: Relationship between prosaccade (PS) and antisaccade (AS) performance.A. Median prosaccade latency and AS directional error rate. B. Percentage of express saccades in the PS task and AS directional error rate. C. Median PS latency and median AS prosaccade error latency. D. Percentage of express saccades in the PS task and median AS error prosaccade latency (AS). E. Percentage of express saccades in the PS task and percentage of ES in AS prosaccade errors. F. The difference between correct AS latency and PS latency calculated for each subject, and AS directional error rate. On each plot the solid black line is the least-squares linear regression line calculated for the whole dataset. Data from ESMs: grey symbols; data from normal subjects: black symbols.
Mentions: The two groups, defined on the basis of their performance on the prosaccade task, exhibited different patterns of performance in the antisaccade task. What then of the relationship between performance in the two different tasks? Performance in the prosaccade task was summarised using median saccade latency for each participant and the percentage of express saccades. We investigated the relationship between these parameters and antisaccade directional error rate (expressed as a percentage) and median ErrPS latency (Figure 6). Antisaccade directional error rate was correlated both with the median latency in the prosaccade task (Figure 6A; r = −0.33, p = 0.003) and with the percentage of express saccades (6B; r = 0.36, p = 0.002). Correlation coefficients were slightly higher between the median prosaccade latency and antisaccade error prosaccade latencies (6C; r = −0.55, p<0.0001) and percentage of express saccades in prosaccade tasks and antisaccade prosaccade error latency (6D; r = 0.43, p<0.0001). The highest correlation coefficient was observed for the relationship between the percentage of express saccades in prosaccade tasks, and the percentage of ErrPS that were express saccades (Figure 6E; r = 0.63, p<0.0001). We also examined whether a general difference in the speed of prosaccade and antisaccade systems might have a strong influence on directional error rate. For each participant we calculated the difference between the median correct antisaccade latency and the median prosaccade latency, and plotted this against the antisaccade directional error rate (Figure 6f). While there was a positive correlation, it was modest (r = 0.32, p = 0.004).

Bottom Line: Differences in behaviour and cognition have been observed in different human populations.However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks).These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population.

View Article: PubMed Central - PubMed

Affiliation: Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom. pcknox@liv.ac.uk

ABSTRACT
Differences in behaviour and cognition have been observed in different human populations. It has been reported that in various types of complex visual task, eye movement patterns differ systematically between Chinese and non-Chinese participants, an observation that has been related to differences in culture between groups. However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks). These participants are defined as "express saccade makers" (ESMs). We then show using the antisaccade paradigm, which requires the inhibition of reflexive responses and the programming and execution of voluntary saccades, that the performance of ESMs is compromised; they have higher antisaccade directional error rates, and the latency distributions of their error saccades again exhibit a higher proportion of low latency express saccade errors consistent with a reduced ability to inhibit reflexive responses. These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population. They suggest a potential unexpected confound relevant to those studies of Chinese versus other groups which have investigated group differences using oculomotor measures, and explained them in terms of culture. The confirmation of higher numbers of ESMs among Chinese participants provides new opportunities for examining oculomotor control.

Show MeSH
Related in: MedlinePlus